If he did, and used soldiers to build it, they would all be committing a federal crime.

President Trump on Friday said that he was considering the declaration of a “national emergency” along the border with Mexico, which he apparently believes would allow him to divert funds from the military budget to pay for a wall, and to use military personnel to build it.

While it is hard to know exactly what the president has in mind, or whether he has any conception about what it would entail, one thing is clear: Not only would such an action be illegal, but if members of the armed forces obeyed his command, they would be committing a federal crime.

Begin with the basics. From the founding onward, the American constitutional tradition has profoundly opposed the president’s use of the military to enforce domestic law. A key provision, rooted in an 1878 statute and added to the law in 1956, declares that whoever “willfully uses any part of the Army or the Air Force” to execute a law domestically “shall be fined under this title or imprisoned not more than two years” — except when “expressly authorized by the Constitution or Act of Congress.”

Another provision, grounded in a statute from 1807 and added to the law in 1981, requires the secretary of defense to “ensure that any activity (including the provision of any equipment or facility or the assignment or detail of any personnel)” must “not include or permit direct participation by a member of the Army, Navy, Air Force, or Marine Corps in a search, seizure, arrest, or other similar activity unless participation in such activity by such member is otherwise authorized by law.”

In response to the Hurricane Katrina disaster in New Orleans, Congress created an express exception to the rules, and authorized the military to play a backup role in “major public emergencies.” But in 2008 Congress and President Bush repealed this sweeping exception. Is President Trump aware of this express repudiation of the power which he is threatening to invoke?

The statute books do contain a series of carefully crafted exceptions to the general rule. Most relevantly, Congress has granted the Coast Guard broad powers to enforce the law within the domestic waters of the United States. But there is no similar provision granting the other military services a comparable power to “search, seize and arrest” along the Mexican border. Given Congress’s decision of 2008, this silence speaks louder than words. Similarly, the current military appropriations bill fails to exempt military professionals from criminal punishment for violating the law in their use of available funds.

It is, I suppose, possible to imagine a situation in which the president might take advantage of the most recent exception, enacted in 2011, which authorized the military detention of suspected terrorists associated with Al Qaeda or the Taliban. But despite President Trump’s unsupported claims about “terrorists” trying to cross the border, it is an unconscionable stretch to use this proviso to support using the military for operations against the desperate refugees from Central America seeking asylum in our country.

It is even less plausible for the president to suspend these restrictions under the National Emergencies Act of 1976. From the Great Depression through the Cold War, presidents systematically abused emergency powers granted them by Congress in some 470 statutes, culminating in the Watergate fiasco. In response, the first section of the 1976 act terminated all existing emergencies and created a framework of checks and balances on the president’s arbitrary will.

If President Trump declared an emergency, Section Five of the act gives the House of Representatives the right to repudiate it immediately, then pass their resolution to the Senate — which is explicitly required to conduct a floor vote within 15 days. Since President Trump’s “emergency” declaration would be a direct response to his failure to convince Congress that national security requires his wall, it is hard to believe that a majority of the Senate, if forced to vote, would accept his show of contempt for their authority.

The Supreme Court’s 1953 decision in Youngstown v. Sawyer would be critical in Congressional consideration of such a decision. In a canonical opinion by Justice Robert Jackson, the court invalidated President Truman’s attempt in 1952 to use his powers as commander in chief to nationalize steel mills in the face of labor strikes. The decision imposed fundamental constitutional limits on the president’s power to claim that a national emergency — in this case, the Korean War — allowed him to override express provisions preventing him from using those powers domestically.

The law is clear; how it would play out is less so. But undoubtedly, we would see a period of passionate debate on Capitol Hill, with scores of representatives, from both parties, condemning the president’s move as an unconstitutional abuse of his powers as commander in chief.

This would play out in public, with millions of service members watching closely. They would immediately be obliged to decide whether to obey President Trump — and risk criminal punishment. For the president to put these men and women in such a position, simply out of petulance over congressional opposition, would be especially unconscionable.

Should the president proceed, he should ask the Office of Legal Counsel to issue an opinion explaining to service members why they would not be “willfully” acting illegally if they heeded the president’s command. But we know this president well enough to know that will not happen.

Instead, he will likely take the most irresponsible path possible, issuing his “national emergency” through a tweet or a question-begging written pronunciamento. Recall how legally flawed his first stabs at the so-called travel ban were; if anything, his willingness to seek legal advice, and the ability of those around him to provide it, has declined since then.

What this all adds up to is a potential crisis much graver than whatever immigration emergencies the president has in mind: A legally ignorant president forcing our troops to choose between his commands and the rule of law in a petty political struggle over a domestic political question.

Question: What does CNN’s Jim Acosta crave more than anything? If you said “attention,” go to the head of the class. It’s a mystery why the White House has given Acosta way more than that. By yanking his “hard pass” after last week’s press conference (don’t ask who was obnoxious; they all were), Acosta has literally become a federal case. CNN filed suit claiming that its reporter’s First and Fifth Amendment rights were violated. More than a dozen news organizations, including Fox, have filed amicus briefs supporting CNN, and even Trump-friendly Fox News judicial analyst Andrew Napolitano has opined that Acosta has a strong case. Mr. Showboat is just where he wants to be — the center of attention — but thanks to President Trump’s gratuitous swipe, he is also a free-press martyr.

Acosta’s technique has been honed for many months — asking questions not to receive answers but to shame. At the November 7 press conference, Acosta rose to “challenge” the president on what he had said about the caravan during the closing days of the campaign. “As you know Mr. President, the caravan was not an invasion. It’s a group of migrants moving up from Central America towards the border with the U.S.”

It’s not Acosta’s job to joust with the president over interpretations of words. Leave that to commentators or politicians.

He could have asked the president where he got his information about Middle Eastern terrorists infiltrating into the caravan, or

what his evidence was that there were many criminals in its ranks.

He might have asked what purpose U.S. troops would serve at the border in light of the Posse Comitatus Act.

He could have asked whether the president thought any of the migrants might have colorable asylum claims.

Instead, he demanded: “Do you think you demonized immigrants?”

Frankly, if Acosta thinks the president demonized immigrants, let him write an op-ed. A press conference is supposed to be about eliciting information. Acosta doesn’t practice journalism so much as performance art.

.. The White House handled this mosquito in about the worst possible way. The president could have declined to call on him. Having called on him and been offended by his tone, the president could have refused to take the bait, saying “You might want to run for office yourself. In the meantime, I’ll call on someone who wants to ask a question, not stage a debate.”

.. Instead, in a fit of petulance, the White House revoked Acosta’s press pass. This is Trump not understanding the import of the office he holds. When Trump the businessman took swipes at press coverage he disliked, it was pique. When the president of the United States does it, it smacks of authoritarianism. Admittedly, the press corps are a high-strung bunch, but this White House

flirts with intimidation,

calling down contempt for them at rallies,

deriding them as the “enemy of the people” (which is an echo of Stalin,

whether Trump recognizes it or not), threatening to sic the FTC on the owner of the Washington Post, and elevating the likes of Gateway Pundit.

Sarah Huckabee Sanders, who cannot be much more honest than her boss and hope to keep her job, issued a tweet explaining that Acosta was exiled because he had accosted the intern who attempted to remove the mic from his hands. “President Trump believes in a free press and expects and welcomes tough questions of him and his Administration. We will, however, never tolerate a reporter placing his hands on a young woman just trying to do her job as a White House intern. . . .”

Anyone who watched the exchange — or looked it up on YouTube — knew that this was risible. Yet Sanders said it anyway and even released a video that had been slightly doctored (by speeding it up) to make it seem that Acosta had been physically swatting at the intern.

Within a few days, Sanders changed her tune, claiming instead that the White House cannot run a smooth press conference if reporters hog the mic. But let’s pause to consider where this White House has settled. Covering up for an intemperate retaliation against a journalist, the spokesman for the president of the United States attempted to rewrite the history that we had all seen with our own eyes just days before.

After Democrats lost the 2016 presidential election, a certain conventional wisdom congealed within the pundit class: Donald Trump’s success was owed to the Democratic abandonment of the white working class and the party’s emphasis on identity politics. By failing to emphasize a strong economic message, the thinking went, the party had ceded the election to Trump.

.. That explanation ignored the uncomfortable fact that Trump’s economic vision was centered on a politics of white identity, charging that immigrants and unqualified minorities were obtaining advantages the average white American could not claim. That left his opponents with a choice: Contest that vision, or let him attack those groups uncontested.

.. the meantime, Trump’s administration has seen that economic message almost entirely subsumed by the focus of congressional Republicans on tax cuts for the wealthy and plans to shrink the social safety net. But even as the message has shifted, there hasn’t been a corresponding erosion in Trump’s support. The economics were never the point. The cruelty was the point.

.. Nevertheless, among those who claim to oppose identity politics, the term is applied exclusively to efforts by historically marginalized constituencies to claim rights others already possess.

.. Trump’s campaign, with its emphasis on state violence against religious and ethnic minorities—Muslim bans, mass deportations, “nationwide stop-and-frisk”—does not count under this definition, but left-wing opposition to discriminatory state violence does.

.. A November panel at the right-wing Heritage Foundation on the threat posed by “identity politics,” with no apparent irony, will feature an all-white panel.

.. But the entire closing argument of the Republican Party in the 2018 midterm elections is a naked appeal to identity politics—a politics based in appeals to the loathing of, or membership in, a particular group. The GOP’s plan to slash the welfare state in order to make room for more high-income tax cuts is unpopular among the public at large. In order to preserve their congressional majority, Republicans have taken to misleading voters by insisting that they oppose cuts or changes to popular social insurance programs, while stoking fears about

.. In truth, without that deception, identity politics is all the Trump-era Republican Party has.

.. Trump considers the media “the enemy of the people” only when it successfully undermines his falsehoods; at all other times, it is a force multiplier, obeying his attempts to shift topics of conversation from substantive policy matters to racial scaremongering.

.. The tenets of objectivity by which American journalists largely abide hold that reporters may not pass judgment on the morality of certain political tactics, only on their effectiveness. It’s a principle that unintentionally rewards immorality by turning questions of right and wrong into debates over whether a particular tactic will help win an election.

.. In the closing weeks of the campaign, the president has promised a nonexistent tax cut to the middle class after two years in which unified Republican control of government produced only a windfall for the rich

.. Trump’s nativism, and the Republican Party’s traditional hostility to government intervention on behalf of the poor, have had a happier marriage than some might have expected.

.. But that wasn’t what Trump promised—rather, his 2016 campaign pledged both generous social-insurance benefits for working-class white Republicans and cruelty for undeserving nonwhites.

.. This approach has drawn predictable criticism from the left for its appeal to prejudice, but somehow, few of the pundits convinced that identity politics poses a threat to democracy have displayed alarm as the president and his party have built a second nationwide campaign around it.

.. Underlying the American discourse on identity politics has always been the unstated assumption that, as a white man’s country, white identity politics—such as that practiced by Trump and the Republican Party—is legitimate, while opposition to such politics is not.

.. When armed agents of the state gun down innocent people in the street, when the president attempts to ban people from entering the U.S. based on their faith, or when the administration shatters immigrant families, these are burdens that religious and ethnic minorities must bear silently as the price of their presence in the United States.

And in the impoverished moral imagination of Trumpist political discourse, any and all white Americans who also oppose such things must be doing so insincerely in an effort to seek approval.

.. America is not, strictly speaking, a center-right or center-left nation. Rather, it remains the nation of the Dixiecrats, in which the majority’s desire for equal opportunity and a robust welfare state is mediated by the addiction of a large chunk of the polity to racial hierarchy. It is no coincidence that the Democratic Party’s dominant period in American history coincided with its representation of both warring impulses and ended when it chose one over the other. The midterms offer a similar choice for the American voter, in rather stark terms.

At the end of last week, the caravan arrived on the doorstep to Mexico. Under pressure from the U.S., Mexico offered the migrants asylum but said it would only let in groups of 150 to 200 people a day to process their requests. Anyone crossing the border illegally would be deported, Mexican officials warned.

The Honduran government estimates that 2,000 migrants returned home. Mexico says another 1,000 or so have applied for asylum. But the majority—about 5,000, according to the Mexican government—crossed the border illegally, mostly on rickety rafts run by human smugglers.

.. “We can’t get to the northern border all together” said Irineo Mujica, the head of People without Borders, a U.S.-Mexico nonprofit that has backed the caravan since its arrival in Guatemala. Such a huge group moving across Mexico days before the U.S. midterms, he added, would embolden Mr. Trump. “If this full caravan arrives to the U.S. border, it would be like a declaration of war,” Mr. Mujica said.

.. Most migrants say they want to get to the U.S. but generally don’t know what legal options they have ahead. Many said they were determined to abandon Honduras, which has among the world’s highest rates of violence. When they saw news on television that a caravan had left from San Pedro Sula heading north, many thought it was the right moment to leave.

.. She said a criminal gang extorted her family business and demanded a “war tax,” calling it that because “if you don’t pay the gang destroys your business and kills you.”

.. For many would-be migrants, leaving in a caravan is attractive because they can avoid paying some $5,000 in smugglers’ fees and are safer traveling in numbers.

.. On Oct. 5, Honduran social activist and leftist politician Bartolo Fuentes shared the information about the caravan on his Facebook account

.. “Most Mexicans are sympathetic to the migrants, so politically it becomes very difficult for the government to move against the caravan given it has such visibility,” he said. “On the other hand, you don’t want to anger the U.S. and be seen as just allowing migrants to cross through your country freely.”

.. On Sunday, Mr. Trump warned the migrants on Twitter that if they didn’t accept Mexico’s offer of asylum, they would be denied entry to the U.S. He said Monday the caravan included “criminals and unknown Middle Easterners,” without offering evidence.

.. For fiscal year 2019, the U.S. plans to send about

$70 million in aid to Guatemala,

$66 million to Honduras and

$46 million to El Salvador,

according to the State Department. Most of the funds go to

violence prevention,

justice and rule-of-law programs, along with

funding for border and narcotics enforcement.

.. Cutting aid to Central American countries would be a mistake, since U.S. aid dollars fund programs that reduce violence, strengthen the justice system, and encourage investment that make them more attractive places for their citizens, said Marcela Escobari, a senior fellow at the Brookings Institution.

.. Studies have shown that once a country’s GDP per capita reaches between $6,000 and $8,000, the gains from migrating somewhere become less attractive, who served under President Barack Obama as head of Latin America for the U.S. Agency for International Development.

“We need to stop these countries from becoming failed states, because that’s what’s going to cause a tremendous exodus,” she said.

.. Immigrants asking for U.S. asylum either at a legal border crossing or upon being arrested by the Border Patrol for crossing illegally are subjected to a “credible fear” interview to decide if their request should be heard by an immigration judge. More than 75% of immigrants pass the so-called “credible fear bar,” according to U.S. government statistics. Those who don’t pass that initial interview are subject to deportation.

.. Immigration authorities can jail asylum seekers until their case is decided, but bed space is at a premium as the Trump administration steps up immigration enforcement both at the border and in the U.S. interior.

For those released into the U.S., a final decision could take years amid a backlog of more than 764,000 cases pending in federal immigration court. During that time, they can live in the U.S. and apply work permits, something Mr. Trump has repeatedly criticized.